HPLC separation of creatine and ornithine

[kiknos]

hey all,


any experiences or suggestions on HPLC separations of creatine and ornithine? it is said they are difficult to be separated. i have no idea to help my friend, and i did a search on google but it seems there is no such article on that.

thanks, and Merry Christmas and Happy New Year2005 (in advance)!

best regards,
kiknos

by the way, thank you all for your great questions and kind replies in this forum in the passing year2004, from which i did learn a lot.

[MG]

I have not analyzed these compounds, but if I had to, I would try a HILIC method.

[Einar Ponten]

Yes, that works nicely!

We have customers running these on ZIC®-HILIC columns.

Contact us if you need more information, then we retrieve successful operational conditions.

[kiknos]

thanks for your kind replies and suggestions!

i also get some suggestions that AQ columns(RP columns but can bear pure aqeous solution) can work.

i wonder what is the advantages for HILIC over AQ if AQ can work and currectly it seems there are a lot of AQ columns(which indicates such products/method can be stable and reliable to some extent).

your opinions? meanwhile, i am really interested in the separation conditions on HILIC for the separation of thetwo amino acids if you have them on hand.

[MG]

I only have experience with silica HILIC columns with LC/MS, and I've found two advantages over "AQ" reverse phase columns (I've never tried the ZIC columns). (1) HILIC will retain compounds that have poor retention even on AQ columns in 100% aqueous; (2) With MS detection, it is much better for sensitivity to elute your compounds in 90% ACN (typical of HILIC mobile phases) as opposed to 100% water.

It isn't a panacea, though. Some compounds will tail badly unless you add large amounts of ammonium formate, which can negate #2 if the amount is high enough. If using only UV detection, I guess retention would be your main advantage.

[Einar Ponten]

Then you never tested the ZIC®-HILIC column. Actually, one of the only designed for the purpose!

[SIELC_Tech]

Here is the method for the separation of creatine, creatinine and histidine (amino acid with additional basic group). Ornithine will behave similarly to histidine

http://allsep.com/makeCmp.php?cmp=Cmp_170